Just because Microsoft Windows itself is a proprietary, closed-source operating system doesn't mean that the software giant isn't open to open source.

Increasingly, it's just the opposite. As the economic downturn drags on, Microsoft (NASDAQ: MSFT) is feeling more pressure to figure out ways that Windows can play nicely with open source applications, which are growing in prominence as companies look for greater flexibility or lower-cost alternatives to proprietary software.

It's a vision that includes having open source software running on top of Windows, which Sam Ramji, senior director of platform strategy at Microsoft, claims has been working well, with more than 80,000 open source software applications now available for Windows.

"We're seeing open source applications adopted on the Windows platform," Ramji told InternetNews.com. "The rationale is that you can use the existing hardware and software investments that you've made to deploy workloads."

"This is an expanding area of focus and we're busier than ever," he said.

But Microsoft's betting the low-cost allure of open source can benefit it, too.

Ramji said one of his chief focuses is on how customers are using the Windows platform in a downturn, when enterprises are deferring non-critical hardware and software purchases. He said that having Windows as a platform play for open source software deployment is key to the company's continued ability to weather the worst of the slowdown.

In particular, Ramji added that he believes the work that Microsoft has done to support PHP and Java on top of Windows is a key part of the resiliency of Microsoft's operating systems business. The company has been working with commercial PHP sponsor Zend for the last several years to improve PHP support on Windows.

Ramji also noted that Robert Youngjohns, president for Microsoft North America, is scheduled to keynote at OSBC on Wednesday and will argue that the fundamentals of technology innovation and improved productivity will help to bring the IT sector back, while showing how computing can help to grow businesses in the current downturn.

Part of that growth potential comes from working with open source firms as a way to develop new solutions that appeal to customers even in the downturn, Ramji added.

"We're seeing demand for some of our joint solutions with Novell around Linux and Windows interoperability," he said.

Novell and Microsoft have an interoperability and patent deal originally signed in November 2006. Since then, Microsoft has also been working with Red Hat to enable Red Hat's Linux to run virtualized on Microsoft's Hyper-V virtualization hypervisor.

That might be one reason that while the economy is a slowdown, Ramji said there hasn't been letup in activity in the open source group that he runs at Microsoft.

Courting open source

Microsoft is continuing to work on making Windows a popular platform for open source application deployments. Ramji noted that Microsoft last week announced the Windows Web App Gallery, which currently includes 10 open source applications that can be easily deployed on Windows.

"There are many more applications we want to add -- another 50 or 60 PHP Web applications," Ramji said.

Ramji added that there is still work that Microsoft can do to further ensure that PHP runs well on Windows. According to Ramji, Microsoft is working with Zend and the PHP community not just on historical PHP releases but also on future releases to ensure that Microsoft can add value to next-generation versions of PHP running on Windows.

Open source patents

While Microsoft is trying to push its message of openness and interoperability, it still sometimes has issues with open source and Linux. Recently, Microsoft launched a patent suit against GPS navigation vendor TomTom, which includes a number of Linux and open source technologies.

But Ramji claimed that patent issues aren't causing any chilling effect on his part of Microsoft's open source plans.

"We've made so much progress in demonstrating a consistent and rational process for open source adoption of Microsoft technologies and interoperability with non-Microsoft platforms," Ramji said. "I feel like we've gained some credit in that area and we do our best. I've been at two significant open source events in the last few weeks and none of attendees have brought up the issues of patents to me."